Endoscope

1. An endoscope comprising: a scope provided with a hard portion at a distal end of a long flexible portion having flexibility; an image capturing portion housed in the hard portion and having an image sensor; a transmission cable inserted into the scope and conductively connected to the image sensor at a distal end via a substrate having a first rigid substrate and a second rigid substrate connected by a flexible hinge, and a voltage converter mounted on the substrate and outputting a constant voltage to the image sensor with respect to an input voltage input to the transmission cable, wherein: the image sensor is mounted on the first rigid substrate, and the voltage converter is mounted on the second rigid substrate.

2. The endoscope according to claim 1 , wherein the voltage converter is a linear regulator.

3. The endoscope according to claim 2 , wherein the voltage converter is an LDO regulator.

4. The endoscope according to claim 1 , wherein the voltage converter and the image sensor are mounted on the same flexible substrate.

5. The endoscope according to claim 1 , wherein a wireless device is mounted on the substrate.

6. The endoscope according to claim 1 , wherein a motor driving device is mounted on the substrate.

7. An endoscope comprising: a scope provided with a hard portion at a distal end of a long flexible portion having flexibility; a pair of image capturing portions with an axis sandwiched therebetween, each image capturing portion of the pair of image capturing portions housed in the hard portion and having an image sensor; a transmission cable inserted into the scope and conductively connected to each image sensor at a distal end via a substrate, and a voltage converter mounted on the substrate and outputting a constant voltage to each image sensor with respect to an input voltage input to the transmission cable, wherein: each of the substrates connected to each of the image sensors disposed in each of the pair of image capturing portions is formed by bending into an L-shape with a sensor connection portion parallel to a back surface of the corresponding image sensor and a cable connection portion perpendicular to the back surface, and each of the image sensors is disposed in a direction in which each of the cable connection portions faces each other with the axis of the hard portion sandwiched therebetween.

8. An endoscope comprising: a scope provided with a hard portion at a distal end of a long flexible portion having flexibility; a pair of image capturing portions with an axis sandwiched therebetween, each image capturing portion of the pair of image capturing portions housed in the hard portion and having an image sensor; a transmission cable inserted into the scope and conductively connected to each image sensor at a distal end via a substrate, and a voltage converter mounted on the substrate and outputting a constant voltage to each image sensor with respect to an input voltage input to the transmission cable, wherein: each of the substrates connected to each of the image sensors disposed in each of the pair of image capturing portions is formed by bending into an L-shape with a sensor connection portion parallel to a back surface of the corresponding image sensor and a cable connection portion perpendicular to the back surface, and each of the image sensors is disposed with each of the cable connection portions facing outward with the axis of the hard portion sandwiched therebetween, and a surface on an opposite side of the image sensor of each of the sensor connection portion connected to the back surface of each of the pair of image sensors is covered with one shading member.